6 ms·

How the Neutrino’s Tiny Mass Could Help Solve Big Mysteries

37 points by theafh 7y ago

blackflame 7y ago
The Neutrino has always fascinated me since I first learned about particles. It's almost not of this realm with the way it interacts with matter compared to everything else.
- atlasland 7y ago
  I'm curious if there's new physics underway that may make neutrino interactions at a large scale feasible. Experiments that I know usually detect one to five neutrinos a year and I'm wondering if we could ever come up with method that can capture orders of magnitude more than that
  - dphidt 7y ago
    It's not quite so bad, with many experiments looking at solar or atmospheric neutrinos seeing hundreds to thousands of neutrino events per year. Experiments at particle accelerator-based neutrino beams can see much larger event rates despite the small cross section, and as one example, the upcoming SBND experiment (https://sbn-nd.fnal.gov/ https://sbn-nd.fnal.gov/) will see 7 million neutrino interactions in about three years.
  - peteradio 7y ago
    Would need to make ultra dense materials which would require subatomic engineering.
    - blackflame 7y ago
      Would such a thing even be attainable on earth without the tremendous forces that collapse atoms into neutrons? Does matter in a neutron density state convert back to atomic density state in the absence of such forces?
      - peteradio 7y ago
        I think it would be unstable in general but perhaps some shielding could be created to help but even so it seems like strong forces would need to be used to hold the ultradense target together.
Majromax 7y ago
> While neutrino oscillation experiments have measured the differences between the mass states, experiments like KATRIN home in on a kind of average of the three. Combining the two types of measurements can reveal the value of each mass state, favoring certain theories of neutrino mass over others. Since the universe's cruel trick seems to be that the Standard Model -- in all its ugly glory -- refuses to be falisified, what is the least surprising outcome for this experiment? Is there a set of neutrino masses that is minimally-illuminating of physics beyond the standard model?
- nxpnsv 7y ago
  In the standard model neutrino masses are 0....
  - Herrin 7y ago
    Adding masses is a trivial extension, though, by giving them masses in the same way that electrons and other leptons do.
- Herrin 7y ago
  There are a few interesting things that we could get from looking at neutrino masses. The first has to do more with the nature of the mass than the mass itself. In the standard model, electrons, muons, and taus get their mass from the Higgs field. There's a way for neutrinos to get their mass in other ways, but it requires them to be their own antiparticles. And this gives a satisfactory answer as to why their masses are so tiny, and suggests some new particles (although at electroweak unification scale, so not anything we're going to achieve with a collider any time soon). There are a number of double-beta decay experiments trying to measure the Majorana mass of neutrinos. The other would be if the neutrino hierarchy is "inverted". The tau is heavier than the muon is heavier than the electron. Right now, with neutrinos, we can only measure the difference in masses. And so it's not clear if the neutrino with the most election portion[1] is the lightest or if the neutrino with the most tau portion is. The latter would be "inverted" from what we expect, and trying to figure out why might be interesting, though I don't know that it immediately implies new physics. There're also other things related to masses that are interesting. Neutrino oscillations are determined by the differences in mass. Looking at these, we might be able to discover more generations of neutrino (beyond electron, mu, and tau), which would be new physics. [1] the mass eigenstates of the neutrino (that is, the things with well-defined masses) are not weak force eigenstates, so they contain mixtures of the electron, mu, and tau neutrinos
shifto 7y ago
Not really related but I like how they are trying to detect neutrinos to discover a supernova before it happens [1]. As the neutrinos leave the star hours before they collapse (because the neutrinos can easily escape the star due to it's low mass). [1] https://en.wikipedia.org/wiki/SuperNova_Early_Warning_System https://en.wikipedia.org/wiki/SuperNova_Early_Warning_System
- particleguy 7y ago
  A small correction- it’s not the small mass of the neutrino that allows it to escape quickly, but the fact that they are electrically neutral, and also do not interact with the strong force and do not get caught by the nucleus of atoms. Photons have no mass, but they arrive after the neutrinos because they are slowed down by being constantly absorbed and remitted by the atoms of the star through the electromagnetic force.
  - shifto 7y ago
    Thanks for clarifying!
  - atlasland 7y ago
    Do you think neutrinos could be used to produce electricity?
    - contravariant 7y ago
      For the sun it's probably easier to capture the 98% of energy that's radiated as light. The sun is by far the best source of neutrinos.
      - saagarjha 7y ago
        For a standard core collapse supernova, the vast majority of the released energy is in the form of neutrinos.
        7y ago
JamesCoyne 7y ago
Dupe: https://news.ycombinator.com/item?id=21268086 https://news.ycombinator.com/item?id=21268086
- dang 7y ago
  Merged thither. Thanks! Edit: oops, this one was posted earlier and that was the dupe. Fixed now.
deleted 7y ago
[deleted]

37 points by theafh 7y ago

The Neutrino has always fascinated me since I first learned about particles. It's almost not of this realm with the way it interacts with matter compared to everything else.

atlasland 7y ago
I'm curious if there's new physics underway that may make neutrino interactions at a large scale feasible. Experiments that I know usually detect one to five neutrinos a year and I'm wondering if we could ever come up with method that can capture orders of magnitude more than that
- dphidt 7y ago
  It's not quite so bad, with many experiments looking at solar or atmospheric neutrinos seeing hundreds to thousands of neutrino events per year. Experiments at particle accelerator-based neutrino beams can see much larger event rates despite the small cross section, and as one example, the upcoming SBND experiment (https://sbn-nd.fnal.gov/ https://sbn-nd.fnal.gov/) will see 7 million neutrino interactions in about three years.
- peteradio 7y ago
  Would need to make ultra dense materials which would require subatomic engineering.
  - blackflame 7y ago
    Would such a thing even be attainable on earth without the tremendous forces that collapse atoms into neutrons? Does matter in a neutron density state convert back to atomic density state in the absence of such forces?
    - peteradio 7y ago
      I think it would be unstable in general but perhaps some shielding could be created to help but even so it seems like strong forces would need to be used to hold the ultradense target together.

Majromax 7y ago

> While neutrino oscillation experiments have measured the differences between the mass states, experiments like KATRIN home in on a kind of average of the three. Combining the two types of measurements can reveal the value of each mass state, favoring certain theories of neutrino mass over others. Since the universe's cruel trick seems to be that the Standard Model -- in all its ugly glory -- refuses to be falisified, what is the least surprising outcome for this experiment? Is there a set of neutrino masses that is minimally-illuminating of physics beyond the standard model?

nxpnsv 7y ago
In the standard model neutrino masses are 0....
- Herrin 7y ago
  Adding masses is a trivial extension, though, by giving them masses in the same way that electrons and other leptons do.
Herrin 7y ago
There are a few interesting things that we could get from looking at neutrino masses. The first has to do more with the nature of the mass than the mass itself. In the standard model, electrons, muons, and taus get their mass from the Higgs field. There's a way for neutrinos to get their mass in other ways, but it requires them to be their own antiparticles. And this gives a satisfactory answer as to why their masses are so tiny, and suggests some new particles (although at electroweak unification scale, so not anything we're going to achieve with a collider any time soon). There are a number of double-beta decay experiments trying to measure the Majorana mass of neutrinos. The other would be if the neutrino hierarchy is "inverted". The tau is heavier than the muon is heavier than the electron. Right now, with neutrinos, we can only measure the difference in masses. And so it's not clear if the neutrino with the most election portion[1] is the lightest or if the neutrino with the most tau portion is. The latter would be "inverted" from what we expect, and trying to figure out why might be interesting, though I don't know that it immediately implies new physics. There're also other things related to masses that are interesting. Neutrino oscillations are determined by the differences in mass. Looking at these, we might be able to discover more generations of neutrino (beyond electron, mu, and tau), which would be new physics. [1] the mass eigenstates of the neutrino (that is, the things with well-defined masses) are not weak force eigenstates, so they contain mixtures of the electron, mu, and tau neutrinos

shifto 7y ago

Not really related but I like how they are trying to detect neutrinos to discover a supernova before it happens [1]. As the neutrinos leave the star hours before they collapse (because the neutrinos can easily escape the star due to it's low mass). [1] https://en.wikipedia.org/wiki/SuperNova_Early_Warning_System https://en.wikipedia.org/wiki/SuperNova_Early_Warning_System

particleguy 7y ago
A small correction- it’s not the small mass of the neutrino that allows it to escape quickly, but the fact that they are electrically neutral, and also do not interact with the strong force and do not get caught by the nucleus of atoms. Photons have no mass, but they arrive after the neutrinos because they are slowed down by being constantly absorbed and remitted by the atoms of the star through the electromagnetic force.
- shifto 7y ago
  Thanks for clarifying!
- atlasland 7y ago
  Do you think neutrinos could be used to produce electricity?
  - contravariant 7y ago
    For the sun it's probably easier to capture the 98% of energy that's radiated as light. The sun is by far the best source of neutrinos.
    - saagarjha 7y ago
      For a standard core collapse supernova, the vast majority of the released energy is in the form of neutrinos.
      - 7y ago

JamesCoyne 7y ago

Dupe: https://news.ycombinator.com/item?id=21268086 https://news.ycombinator.com/item?id=21268086

dang 7y ago
Merged thither. Thanks! Edit: oops, this one was posted earlier and that was the dupe. Fixed now.

deleted 7y ago

[deleted]